It is standard practice to provide the front seat of an automobile at each sitting position with a head restraint, normally constituted as an upward extension of the seat, or a bar or guide carrying a cushion at the level of the head of a person sitting in the seat. The purpose of such a head restraint is to prevent a passenger's or driver's head from being snapped back excessively in the event of a rear-end collision. In addition to this protection against whiplash injury, such a head restraint is often regarded as a desirable amenity, as it allows the person using the seat to lean his or her head back for sleeping or resting.
It has been suggested to provide such head restraints for the rear-seat passengers in a passenger vehicle. The basic requirements of such a rear-seat head restraint are that it act as well in preventing whiplash as the standard front-seat head restraints, and at the same time not block the driver's view through the rear vehicle window.
Accordingly it has been suggested in German Patent publication No. 1,608,142 to provide a tough and slightly elastic net across the passenger compartment and immediately behind and above the rear seat. Although this system has the advantage of offering little obstruction to rearward view, it nonetheless offers only minimal protection against whiplash injury, as the net is normally not sufficiently strong to withstand a strong backward force.
It has also been suggested in German Patent publication No. 2,138,151 to provide a heavy strap which extends at head level across the back of the vehicle above the rear seat back. Although such a system has the advantage of considerable simplicity, it nonetheless presents an obstruction to view, and also offers a normally inadequate protection for the rear seat passengers. To eliminate the obstruction when no passengers are in the rear seat it is a relatively simple matter to unhook this head-restraint strap, however such unhooking is a normally bothersome operation, as is rehooking it when the rear seat is to be used by a passenger.